A meta-analysis of alcohol drinking and oral and pharyngeal cancers: results from subgroup analyses

AIMS: To quantify the magnitude of the association between alcohol and oral and pharyngeal cancer (OPC) by sex, smoking habits, type of alcoholic beverage and other factors. METHODS: We combined findings from all case-control and cohort studies published until September 2010 and present in this article the results classified by these factors, using a meta-analytic approach. Summary relative risks (RRs) were obtained using random-effects models; heterogeneity was assessed using the χ(2) test. RESULTS: The association between alcohol and OPC risk was similar in men and women, with similar dose-response relationships. No notable differences were found with respect to geographic area and other factors, both for drinking overall and heavy (≥4 drinks/day) drinking. Among never/non-current smokers, the pooled RRs were 1.32 (95% confidence interval, CI, 1.05-1.67) for drinking, and 2.54 (95% CI, 1.80-3.58) for heavy drinking. The corresponding RRs in smokers were 2.92 (95% CI, 2.31-3.70) and 6.32 (95% CI, 5.05-7.90). The pooled RRs for any drinking irrespective of smoking were 2.12 (95% CI, 1.37-3.29) for wine-, 2.43 (95% CI, 1.92-3.07) for beer- and 2.30 (95% CI, 1.78-2.98) for spirits-only drinking. The corresponding RRs for heavy drinking were 4.92 (95% CI, 2.80-8.65), 4.20 (95% CI, 1.43-12.38) and 5.20 (95% CI, 2.77-9.78). CONCLUSION: The alcohol-related RRs are similar with respect to sex, geographic area and type of alcoholic beverage. The association between alcohol and OPC is stronger in smokers than in non-smokers.